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Electronic Flora of South Australia Species Fact Sheet

Audouinella caespitosa (J. Agardh) Dixon 1976: 590.

Phylum Rhodophyta – Class Florideophyceae – Order Acrochaetiales – Family Acrochaetiaceae

Selected citations: Dixon & Irvine 1977b: 84, fig. 18. Millar & Kraft 1993: 6.


Callithamnion caespitosum J. Agardh 1851: 18.

Rhodothamniella caespitosa (J. Agardh) Feldmann in Bidoux & Magne 1989: 34.

Callithamnion botryocarpum Harvey 1855a: 563.

Acrochaetium botryocarpum (Harvey) J. Agardh 1892: 48. Levring 1953: 484, figs 18–20. Woelkerling 1970: 159, figs 1–31.

Audouinella bottyocarpa (Harvey) Woelkerling 1971: 37. Garbary 1987: 30. Guiry et al. 1987: 229, figs 1–23. Schneider 1983: 5, fig. 1 g-1. Schneider & Searles 1991: 196, figs 226,227.

Acrochaetium grande sensu Levring 1953: 480.

Colaconema botryocarpum (Harvey) Stegenga 1985: 317, fig. 19.

Acrochaetium polyrhizum (Harvey) J. Agardh 1892: 48. Levring 1953: 481, figs 14, 15A–C.

Thallus (Fig. 10I) red to grey-red, largely to entirely epiphytic or epilithic, caespitose, usually 2–6 mm high; original spore non-persistent. Prostrate system consisting of irregularly branched filaments remaining largely free from one another or forming an endophytic funiform mass (Fig. 10I) of entangled filaments or a pseudoparenchymatous disc, sometimes supplemented by corticating rhizoidal filaments descending from the lower portions of the erect axes. Erect filaments (Fig. 10I, J) freely and irregularly branched, sometimes terminating abruptly in multicellular hair-like prolongations or gradually tapering towards the tips. Cells (Fig. 103) of erect filaments cylindrical, (10–) 15–20 (–30) µm in diameter and 30–120 µm long (L/D 1–6 in main axes), tapering to 6–15 µm in diameter near the apices; each cell with (2–) 4–6 or more rhodoplasts (Fig. 10J) (Guiry et al. 1987, p. 232) each with a central pyrenoid, usually closely adjacent and appearing as a single parietal lobate rhodoplast with (1–) 2–8 (–18) pyrenoids. Cells of hair-like prolongations 3–6 µm in diameter and up to 125 µm long with weakly developed rhodoplasts with or without pyrenoids. Unicellular hairs unknown.

Reproduction: Monosporangia (Fig. 10J) ovoid, 12–18 (–24) µm in diameter and 18–25 (–40) µm long, sessile or stalked, single, in pairs, or rarely in groups of 3–5, adaxial on the lower cells of laterals or more scattered.

Thalli monoecious or dioecious. Carpogonia (Fig. 10K) terminal on 1–2-celled stalks usually situated near the axils of laterals, stalk cells occasionally giving rise to a short, unbranched sterile filament shortly before or after fertilization. Fertilized carpogonium dividing transversely or rarely remaining undivided after fertilization and giving rise to branched gonimoblast filaments (Fig. 10L) bearing terminal ovoid carposporangia (Fig. IOM) 20–25 µm in diameter and 25–35 µm long, 12–25 per carposporophyte. Spermatangia (Fig. 10N) ovoid to globose, 3–5 µm in diameter and 4–6 µm long, borne singly, in pairs, or in clusters, sessile or stalked.

Tetrasporangia (Fig. 10 0) 18–24 µm in diameter and 20–40 µm long, cruciately divided, usually on unicellular stalks, single or in pairs, on lower cells of laterals.

Type from Brest, France; lectotype in Herb. Agardh, LD, 18011.

Selected specimens: King George Sound, W. Aust. (Harvey, 1854; AD, A18165, isolectotype of A. botryocarpa). Elliston, S. Aust., on Codium pomoides, upper sublittoral (Woelkerling, 16.v.1968; AD, A32292 -"Marine Algae of southern Australia" No. 62b). Cape Jervis, S. Aust., on Scytosiphon lomentaria, lower eulittoral (Mitchell, 29.viii.I954; AD, A19795). American R. inlet, Kangaroo I., S. Aust., on Scytosiphon lomentaria on buoy (Woelkerling, 30.x.1966; AD, A30878). Port Elliot, S. Aust., on Amphibolis antarctica, upper sublittoral (Woelkerling, 28.vii.1967; AD, A32238). Petrel Cove, Victor Harbor, S. Aust., on Scytosiphon lomentaria, lower eulittoral (Woelkerling, 14.viii.1967; AD, A31926 -"Marine Algae of southern Australia" No. 62c). Robe, S. Aust., on Codium fragile in reef pools (Woelkerling, 10.ii.1968; AD, A32283 -"Marine Algae of southern Australia" No. 62a). Port Fairy, Vic. (Harvey, 1854; AD, A8304, isolectotype of Callithamnion polyrhizum Harvey). Apollo Bay, Vic., on Scytosiphon lomentaria (Woelkerling, 23.i.1967; AD, A31189 -"Marine Algae of southern Australia" No. 62d). Point Lonsdale, Vic., on Chordaria cladosiphon in reef pools (Woelkerling, 21.i.1967; AD, A30886). White Beach, Wedge Bay, Tas., on Polycerea nigrescens, upper sublittoral (Wollaston & Mitchell, 29.ii.1964; AD, A27681). Port Arthur, Tas., on Codium fragile (Cribb 48.5, 29.iii.1950; AD, A20435).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Portugal to the Netherlands and southern England; Ireland; N. Carolina, U.S.A.; South Africa; New Zealand.

In southern Australia, from Bunbury, W. Aust., to Point Lonsdale, Vic., and around Tasmania; Coffs Harbour, N.S.W.

Taxonomic notes: A. caespitosa is one of the commonest species of Audouinella in southern Australia, found on a wide variety of hosts. It is distinguished by its habit, dimensions, cells with 2–8 (–18) pyrenoids, and carposporophytes with 12–25 carposporangia.

Bidoux & Magne (1989) have presented strong evidence that A. botryocarpa is identical to the European A. caespitosa, which they follow Feldmann (1954, p. 68) in placing under Rhodothamniella Feldmann, a genus validated in Christensen (1978, p. 67) and distinguished by having several rhodoplasts, each with a pyrenoid, per cell. The type species of Rhodothamniella is R. floridula (Dillwyn) J. Feldmann in Christensen, which however has a minute gametophyte in contrast to R. caespitosa where the gametophyte and sporophyte are of similar size.


AGARDH, J.G. (1851). Species Genera et Ordines Algarum. Vol. 2, Part 1, 1–336 + index. (Gleerup: Lund.)

AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.

BIDOUX, C. & MAGNE, F. (1989). Étude de quelques Acrochaetiales (Rhodophyta) devant étre rapportées au genre Rhodothamniella. Cryptogamie, Algol. 10, 33–55.

CHRISTENSEN, T. (1978). Annotations to a textbook of phycology. Bot. Tidsskr. 73, 65–70.

DIXON, P.S. & IRVINE, L.M. (1977b). Seaweeds of the British Isles. Vol. 1, Rhodophyta. Part I, Introduction, Nemaliales, Gigartinales. [British Museum (N.H.): London.]

DIXON, P.S. (1976). Appendix I. In Parke, M. & Dixon, P.S., Check-list of British marine algae - third revision. J. mar. biol. Ass. U.K. 56, 527–594.

FELDMANN, J. (1954). Inventaire de la Flora Marine de Roscoff. Algues, Champignons, Lichens et Spermatophytes. Travaux Stn Biol. Roscoff. Suppl. 6, pp. 1–152.

GARBARY, D.J. (1987). The Acrochaetiaceae (Rhodophyta): An annotated bibliography. Bibl. Phycol. 77, 1–267.

GUIRY, M.D. KEE, W.R. & GARBARY, D.J. (1987). Morphology, temperature and photoperiodic responses in Audouinella botryocarpa (Harvey)Woelkerling (Acrochaetiaceae, Rhodophyta) from Ireland. Glom. Bot. Ital. 121, 229–246.

HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Ir. Acad. 22, 525–566.

LEVRING, T. (1953). The marine algae of Australia. I. Rhodophyta: Goniotrichales, Bangiales and Némalionales. Arkiv för Bot. Ser. 2, 2, 457–530.

MILLAR, A.J.K. & KRAFT, G.T. (1993). Catalogue of Marine and Freshwater Red Algae (Rhodophyta) of New South Wales, including Lord Howe Island, South-western Pacific. Aust. Syst. Bot. 6, 1–90.

SCHNEIDER, C.W. & SEARLES, R.B. (1991). Seaweeds of the Southeastern United States. (Duke Univ. Press: Durham.)

SCHNEIDER, C.W. (1983). The red algal genus Audouinella Bory (Nemaliales: Acrochaetiaceae) from North Carolina. Smithsonian Contr. Mar. Sci. No. 22, pp. 1–25.

STEGENGA, H. (1985). The marine Acrochaetiaceae (Rhodophyta) of southern Africa. S. Afr. J. Bot. 51, 291–330.

WOELKERLING, W.J. (1970). Acrochaetium botryocarpum (Harv.)J. Ag. (Rhodophyta) in southern Australia. Br. phycol. J. 5, 159–171.

WOELKERLING, W.J. (1971). Morphology and taxonomy of the Audouinella complex (Rhodophyta) in southern Australia. Aust. J. Bot. Suppl. 1, 1–91.

The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.

Author: W.J. Woelkerling & H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustrations in Womersley Part IIIA, 1994: FIG. 10 1–0.

Figure 10 image

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Fig. 10. A–H. Audouinella dictyotae (A, B, E–H, AD, A28372; C, D, AD, A31667). A. Branching pattern, with prostrate system, erect branches and clusters of carposporangia. B. Prostrate system shown in sectional view on Dictyota thallus. C. Branches with monosporangia. D. Branch with monosporangia and cells with rhodoplasts with one to four pyrenoids. E. Branch with bisporangia. F. Branches with carpogonia on stalk cells. G. Mature carposporophyte. H. Branch with spermatangia. I-0. Audouinella caespitosa (I, J, AD, A32283; K–N, AD, A30878; 0, AD, A19795). I. Branching pattern with prostrate system of plant on Codium. J. Erect branches with monosporangia and rhodoplasts each with a pyrenoid shown in some cells. K. Mature carpogonium. L. Young carposporophyte. M. Mature carposporophyte. N. Branch with spermatangia. 0. Branch with tetrasporangia. [B–H after Woelkerling 1971; K-0 after Woelkerling 1970.]

Figure 1 image

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Fig. 1. A, B. Porphyridium purpureum (AD, A59695). A. Cells in patches on Dictyota fenestrata. B. Cells each with a rhodoplast and central pyrenoid. C. Chroodactylon ornatum (AD, A19851). Thallus showing branching pattern and cell detail. D, E. Stylonema alsidii (AD, A58642). D. Branching pattern. E. Cells each with a stellate rhodoplast and pyrenoid. F, G. Stylonema cornu-cervi (AD,A58644). F. Thallus (on Caulerpa) showing cell arrangement. G. Cells each with a rhodoplast and pyrenoid. H. Erythrocladia irregularis (on AD, A31991 of Chaetomorpha linum). Thallus showing branching pattern of cells and cell detail. I. Erythrocladia subintegra (AD, A58641). Thallus showing branching pattern of cells and detail in a few.

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